7.12. Using the PAUSE instruction in InnoDB spin loops

Synchronization inside InnoDB frequently involves the use of
spin loops (where, while waiting, InnoDB executes a tight loop
of instructions repeatedly to avoid having the InnoDB process
and threads be rescheduled by the operating system). If the spin
loops are executed too quickly, system resources are wasted,
imposing a relatively severe penalty on transaction throughput.
Most modern processors implement the PAUSE instruction for use in
spin loops, so the processor can be more efficient.

Beginning with 1.0.4, the InnoDB Plugin uses a PAUSE instruction
in its spin loops on all platforms where such an instruction is
available. This technique increases overall performance with
CPU-bound workloads, and has the added benefit of minimizing power
consumption during the execution of the spin loops.

Using the PAUSE instruction in InnoDB spin loops is transparent
to the user. User does not have to do anything to take advantage
of this performance improvement.